A field-effect transistor (FET) may be a transistor that relies on an electric field to control the conductivity of a “channel” in a semiconductor material. A FET, like all transistors, may be thought of as a voltage-controlled current source. Some FETs may use a single-crystal semiconductor wafer as the channel, or active region. A terminal in a FET may be one of a gate, a drain, or a source. The voltage applied between gate and source terminals may modulate the current between the source and the drain.
Millions of such FET devices may be connected to form a microprocessor, a memory, or a logic interface chip. As the number of the FETs increases and the available energy is diminished, new approaches must be developed that allow the standard operation with significantly less voltage.
Portable products, such as cellular telephones, personal video players, cameras, camcorders, and portable video games are battery powered. These products must be capable of performing across a wide and reduced voltage range. The physical geometries of these FET devices have not deviated very much while their size has greatly been reduced.
Some of the latest developments in FETs may include High-K/metal gate (HK/MG) FETs may operate between 0.8 and 1.0 volts, Trigate FETs may operate between 0.6 and 0.9 volts, III-V/Ge QW FETs may operate between 0.5 and 0.6 volts, and Sub-threshold-slope Transistors for Electronics with Extremely-low Power (STEEP) transistors may operate between 0.25 and 0.4 volts. Transistors in the STEEP group may include ionization metal oxide semiconductor (IMOS) transistors, Green Field Effect Transistors (gFET), or Tunneling Field Effect Transistors (TFET).
Historically the reduction in gate length geometries in the deep sub-micron semiconductor processes has been accompanied by an increase in leakage current. The goal of the newest generations of deep sub-micron technologies is to shorten gate length technologies, decrease the threshold voltage (Vt) without having an increase in the leakage current (Ioff) or short channel effect (SCE). The SCE can not be controlled in today's technology due to junction sheet resistance and gate tunneling.
Today's conventional devices use diffusion based technologies which may limit the sub-threshold-slope to approximately 60 mV. The applications of today require transistor devices that can scale the Vdd required for reliable operation.
Thus, a need still remains for an integrated circuit system with band to band tunneling. In view of the increasing trend toward higher integration and lower voltage batteries, it is increasingly critical that answers be found to these problems. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to reduce costs, improve efficiencies and performance, and meet competitive pressures adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.